Programmable logic arrays (PLA's) are useful mechanisms for implementing complex binary logic functions on semiconductor integrated circuit chips. They provide a regular and orderly structure for implementing irregular and complex combinational logic functions. They are more flexible and are easier to design than are other types of logic structures. A typical programmable logic array (PLA) and some of its uses are described at pages 79-88 of a textbook entitled Introduction to VLSI Systems, by Mead and Conway, published by Addison-Wesley Publishing Company, Reading, Mass. 1980.
Space is invariably a matter of considerable importance on an integrated circuit chip. The usual objective is to maximize the number of circuits and circuit structures that can be located on a single chip. In spite of their various advantages, programmable logic arrays sometimes require more space on a chip than is desired.